Why are males often more physically aggressive

From secondary sources I ve read that male and female humans are equally aggressive (how this is measured I do not know) but that males are more physically aggressive. But that a big part of the difference stems from male vs male aggression. For example, from what I can see from internet article statistics (not really statistics), females and males are similar in counts of physical domestic aggression. The term I keep coming across to describe humans (and other species) is serial pair bonders or